To the right of the church doors is a marble sculpture of the Last Supper. Dating to 1898, the sculpture was originally in the main altar at Sacred Heart Church and was moved here when the former church was deconsecrated and the downtown parishes combined in 1971.

Enter through any of the three sets of large panel doors interior of the oldest Catholic Church building in the state of Georgia. On the large arch above the steps features seven circles depicting the seven sacraments of the church. Two lines of columns divide the nave into two side aisles and a center section. The columns divide the length of the nave into six bays. The floor of the last bay at the Sanctuary is raised approximately one foot. Below the ceiling, plaster arches span from the exterior walls to the columns and from column to column lengthwise of the building. The arched panels separating the bays at the ceiling are stenciled with symbols relating to Christ going toward the altar and symbols of the apostles coming back from the altar. The ceiling between the arches is vaulted from the exterior wall to the column line and between column lines across the building. At the Apse, the building projects as a half octagon open to the Nave and having a vaulted ceiling. On the right and left of the sanctuary are the chapels, dedicated to Saints Mary and Joseph, which are connected by large open arches, each contains an altar.

The interior walls are of stuccoed brick masonry completely restored in 1998 to the original light brown color. The floor of the foyer is concrete with a stone surface. The ceiling and arches are made of plaster on wood lath. The altars, three in number are made of Tennessee marble. The floor of the main area are wood with marble tiles at the aisles and the sanctuary.

The interior width is 69 feet and the height is 47 feet from floor to ceiling. Three distinct and transverse arches supported by twelve ornamental iron columns span the ceiling. The ornate columns are painted in gilt and a dark coral, in a diamond-shaped pattern centered with a floral motif. Other painted detailing highlights the arches of the vaults. Of the three frescos, which originally decorated the semi-dome of the sanctuary, only the center one remains. (The side arches of the vault were painted to blend with the center one during the 1998 restoration of the church.)

The principle openings in the church consist of six large stained glass windows on each side, a large one in front above the entrance doors, and three in the rear. Above the front window a rose window, and above the chapel altars are two other rose windows.

Above the organ loft is open to the Nave and a balcony at this level projects into the Nave about eleven feet. The organ loft has a vaulted ceiling matching that of the Nave.

At the beginning of the central aisle is an ornately carved wooden baptismal font topped by a small sculpture of John the Baptist baptizing Jesus. Flanking the center aisle are two marble fonts with holy water.

Between St. Joseph's altar and the main altar is a large crucifix donated by a parishioner in 1894.

The main altar and sanctuary are separated from the nave by a marble altar rail with beautiful brass gates. The original wooden altar railing were replaced with marble railing and ornate bronze gates around 1905. Marble tiling was also added to the aisles at this time. Close inspection of the brass gates revels many Christian symbols. The four plaques on the gate display symbols of Christ: a lantern (the Light of the world); carpenter's tools; whips and a sponge with bitter wine (symbols of the Crucifixion); and nails (also from the Crucifixion.) Surrounding these are fish (symbols of the Eucharist), a pelican (symbols of Christ - it feeds its young with its own flesh) and a lamb with a book with seven seals (from the book of Revelation.)

Turn toward the back of the church for the best view of the historic Jardine tracker pipe organ located in the balcony. The organ is the largest Jardine organ still in existence and the oldest of its size still in use in the South. Because of the Civil War the organ was not installed in the church until 1868, completed restored in 1993, it is still used in services.